DaveHooper: Am I right in thinking the coldfire bdm support in gdb does not actually support the registers of the 5249 (MBAR2, RAMBAR2, ...)? I guess those are not so important but that's something else that probably needs addressing at some point (and giving back to the community)

LinusNielsenFeltzing: Correct. It doesn't have support for the 5249 control registers. Some day, I might send them a patch...

Connectors

Clarification regarding the TEA/TA signal

The TEA signal in the BDM connector is used for terminating a hung bus access, i.e a bus error. The 68xxx family has a TEA signal to terminate a bus cycle when TA isn't asserted by the Chip Select logic. This generates a Bus Error on the 68xxx family. However, the 5249 doesn't have a TEA signal. Instead, the watchdog timer (SWT) takes care of the bus termination by asserting TA if the software doesn't respond to the IACK cycle of the watchdog timer interrupt.

The debugger has to be able to terminate a hung bus cycle. It does so by asserting the TEA/TA signal, which generates a bus error on the 68xxx and terminates the bus cycle normally on the 5249.

Debugging with BDM/GDB

KEEPACT and PW_EN

On the H1xx, the power is kept on by setting PW_EN (H1xx) / KEEPACT (H3xx) high. This is done by setting GPIO51 high, or by pulling up the signal with a 100K resistor. Both H1xx and H3xx has an unmounted resistor for this purpose.